The US, which leads the coalition fighting ISIL, complained Moscow did not use formal channels to give advance notice of its air strikes to Washington.

Russian Foreign Minister Sergei Lavrov has rejected accusations that Moscow's air strikes in Syria are aimed at targets other than the Islamic State of Iraq and the Levant (ISIL) group and have hit civilians.

"The rumours that the target of these air strikes are not ISIL positions are unfounded," he told journalists after meeting US counterpart John Kerry in New York on Thursday, adding that he has "no data" on civilian casualties.

Saudi Arabia demanded that Russia end its military operations against targets in Syria, a Saudi diplomat said in remarks broadcast by Saudi-owned al-Arabiya television.

Speaking at the United Nations in New York on Wednesday, Abdallah Al-Mouallimi said that the ISIL group was not present in the areas that were attacked by Russian jets.

"The delegation of my country expresses its profound concern regarding the military operations which Russian forces have carried out in Homs and Hama today, places where ISIS (ISIL) forces are not present. These attacks led to a number of innocent victims. We demand it stop immediately and not recur," Mouallimi said.

"As for those countries that have claimed recently to join in the fight against ISIS (ISIL) terrorism, they can't do that at the same time as they support the terrorism of the Syrian regime ... "

US, NATO and the Syrian opposition on Wednesday expressed concern that the Russian bombardments also targeted Western-backed rebels.

President Vladimir Putin called Wednesday's operation a pre-emptive strike against ISIL, and the Russian defence ministry said its warplanes targeted and destroyed eight positions belonging to the group.

US Secretary of State John Kerry said Russia and the US will begin military talks "as soon as possible, perhaps even as soon as tomorrow" to de-escalate the situation, after a meeting with Russian Foreign Minister Sergey Lavrov late on Wednesday in New York.

Speaking to journalists on the sidelines of the UN General Assembly, he said that the Russian air force was cooperating with the Syrian pro-government military to target "exclusively" ISIL targets, adding that the Russian defence ministry has stated on its website the targets and objectives of its air strikes in Syria.

"Air force jets, equipped with modern technology, carried out strikes on eight targets," the Russian defence ministry said on its website on Wednesday.